TIDE TURNS IN FAVOR OF RECYCLING WASTEWATER

City Council’s support of purification plan reflects big shift in public attitudes

Nearly a decade ago, a city survey showed that three-quarters of San Diegans turned up their noses at the thought of using wastewater purified into tap water — a process that critics snubbed as “toilet to tap.”

Last week, the City Council voted to move ahead with a plan to purify 15 million gallons per day of recycled wastewater, confident that the tide of public opinion had turned in its favor. The decision was bolstered by a recent poll showing that 73 percent of San Diegans now support the conversion process.

Council members voted unanimously to pursue a full-scale plant to filter local wastewater, and they asked city staff to report back with detailed cost and construction estimates. They expect to vote on a final plan in about a year; construction of a purification facility and pipeline could take a decade.

The shift in public sentiment, officials said, reflects years of outreach about the safety of purified water and changing opinions among city leaders, along with hard lessons about dwindling water supplies and soaring rates. Squeamishness toward reusing flushed flows has given way to the reality of water shortages.

“There’s been more of a dialogue in the state about water availability, and I think people are more informed about water,” said Councilman David Alvarez, chairman of the city’s Natural Resources and Culture Committee, which has helped develop the purification plan.

For two years, the city has run a demonstration project, filtering a million gallons of recycled water per day through a series of treatments to produce a product of the same crystalline quality as distilled water.

Most San Diegans are fine with that, according to a poll of 816 city residents conducted by San Diego State University researcher Richard Parker. The survey found that 73 percent of respondents somewhat or strongly favored treating recycled wastewater for use as tap water, up from just 26 percent in 2004.

To persuade residents about the safety of this purified water, city officials have drawn up educational materials and produced a short video. They’ve hosted tours of the demonstration project for civic, school and Scout groups. Local opinion makers have weighed in as well.

In 2007, for example, former Mayor Jerry Sanders said at a news conference that he would oppose “toilet to tap,” according to a TV report. Three years later, Sanders told Voice of San Diego that he supported the project, adding that he wouldn’t “quibble with scientists.”

Advocates of the project point out that purifying water is hardly new. Nature has been doing it forever, and still filters water through the natural waterways we rely on for imports. Scores of water-treatment facilities dump their product into the channels of the Colorado River and the State Water Project, which together supply most of the San Diego region’s water.

A San Diego city report describes the proposed purification process as the “urban water cycle” — a “sped-up version” of natural filtration.

“The study showed that the water, once purified, is cleaner than the water that is flowing through our taps right now,” said Lani Lutar, executive director of the Equinox Center and co-founder of the San Diego Water Reliability Coalition, an alliance of business and environmental groups. “In fact, the water that comes out of our taps right now has been recycled dozens of times over.”

At the demonstration project in San Diego’s North City Water Reclamation Plant, an array of shiny tanks and tubes and filters recycle water to sparkling purity, said Amy Dorman, the senior engineer heading the operation.

The process starts with microfiltration: rows of plastic tubes containing bundles of hollow membranes. Microscopic pores on their surfaces allow water molecules in, filtering microbes and other contaminants out. The purified water travels through the center of the strawlike membranes.

From there it flows to reverse-osmosis units, which force the water through filters at high pressure to screen out salts and other solids. Water from each canister feeds into an individual spigot, and workers test the water’s quality. In the final stage, intense ultraviolet light zaps any remaining contaminants.

The overall process captures about 80 percent of the recycled wastewater and flushes out the remainder as waste.

The final water is void of just about everything. The only remains are trace amounts of products such as the household disinfectant triclosan, fire-extinguishing fluid, artificial sweeteners, a pharmaceutical agent used in X-rays, strontium and hexavalent chromium.

Those chemicals appear in parts per trillion, leaving the water cleaner than standard drinking water, Dorman said. Purified water has about 3 percent of the dissolved salts and minerals of San Diego’s drinking water, and about 4 percent of its organic carbon content.

If the wastewater purification project goes citywide, San Diego would send the water through a 22-mile pipeline to the San Vicente Reservoir, where it would mix with captured rainfall and imported water. The blend would then be pumped to a drinking-water facility for distribution to homes and businesses.

The purification plant and pipeline would cost an estimated $369 million to build and about $15.5 million per year to run, the city report stated. That means purified wastewater would cost about $2,000 per acre-foot, an amount that serves two households for a year. That’s roughly what water from the planned desalination plant in Carlsbad will cost.

However, reducing wastewater dumped at sea could help the city avoid a $1 billion upgrade to the Point Loma Wastewater Treatment Plant. That savings could offset water purification expenses, cutting the effective cost of purified water in half, the report stated.

By super-treating purified water to better than drinking water standards, Dorman said, the city aims to address both public safety and public comfort levels. Existing water purification plants in Orange County, Virginia, Texas, Arizona and Singapore have safely used similar multi-step systems for years or decades, she said.

She and other city officials are mindful of the “yuck factor.”

“This water originated as wastewater,” Dorman said. “So the sense is you’ve got to get as much out of it as possible before it re-enters the water supply.”

Charles Fleischer, a longtime consumer of bottled water, takes purified water with a grain of salt.

“I don’t think there’s any doubt that technology exists to purify recycled water so that it’s potable,” he said last week while filling half a dozen five-gallon water coolers at AC Water Store in Rancho Bernardo.

Instead, he worries about failures in maintenance and monitoring. He points to the San Onofre Nuclear Generating System, which has been shut down since January 2012 because of faulty parts and botched calculations.

“Given our growing population, we need to increase our water resources,” Fleischer said. “I think we need to do whatever we can to increase the water supply, as long as it’s safe.”